Question

Inside my Mule ESB 3.3.0 app, running in standalone mode, I have a transformer that calls Groovy code that is included as a maven dependent jar. In my groovy code, I am calling a Java object that has a newInstance() static method, like so:

TransformerFactory.newInstance("net.sf.saxon.TransformerFactoryImpl", null)

This is causing errors in Groovy because I think its trying to call the Groovy enhanced Class.newInstance() method. This does not happen when running outside Mule standalone (see update below for description of test). How can I make it call the Java method and not the Groovy one?

Here is a snippet of my stack trace. You can see its calling DefaultGroovyMethods.newInstance(). But I want to call the javax.xml.transform.TransformerFactory.newInstance(String, ClassLoader) method instead. How?

groovy.lang.GroovyRuntimeException: Could not find matching constructor for: javax.xml.transform.TransformerFactory(java.lang.String, null)
at groovy.lang.MetaClassImpl.invokeConstructor(MetaClassImpl.java:1459)
at groovy.lang.MetaClassImpl.invokeConstructor(MetaClassImpl.java:1375)
at org.codehaus.groovy.runtime.InvokerHelper.invokeConstructorOf(InvokerHelper.java:824)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.newInstance(DefaultGroovyMethods.java:18025)

UPDATE:
More info about the runtime environment. The Groovy code is packaged as a jar file and called from a Mule ESB app. Mule 3.3.0 ships with groovy-all-1.8.6.jar.

UPDATE2:
I did some further tests and compiled a Groovy class into a jar file and called it from a standalone Java program and did not experience this issue. This leads me to believe that it is an issue running from the Mule 3.3.0 standalone environment. I am adding a mule tag to this post. Hopefully a Mule expert can tell me what is going on.

Answer 1

With some help from the Groovy user mailing list, we determined that there must be another jar on the mule classpath that is providing the javax.xml.transformer.Transformer class. I added this sample code:

Class klass = TransformerFactory.class; 
URL location = klass.getResource('/'+klass.getName().replace('.', '/')+".class"); 

And sure enough! Mule is adding their own XML API jar.

TranformerFactory JAR: jar:file:/D:/java/mule/mule-standalone-3.3.0/lib/endorsed/xml-apis-1.3.04.jar!/javax/xml/transform/TransformerFactory.class

Why are you overriding the JDK Mule?

My work around was to instantiate the Saxon TransformerFactory directly. Its not very elegant, but my only option.

tFactory = new net.sf.saxon.TransformerFactoryImpl()